1. Field of the Invention
The present invention relates to a method for diagnosing an operating status of a drive device in a drive system, in particular of a motor vehicle, having at least two drive devices, in particular an electric machine and an internal combustion engine, and at least one separating clutch, which couples the drive devices in an adjustable way. Furthermore, the present invention relates to a diagnostic device and a drive system.
2. Description of Related Art
Drive systems having multiple drive devices which may be coupled in an adjustable way with the aid of at least one separating clutch may be operated in various operating modes. For example, operation using only one of the drive devices may be provided, but also, on the other hand, by engaging the separating clutch, operation using multiple drive devices may be provided. Such drive systems are frequently designed as hybrid drive systems, i.e., they have at least two different drive devices. In most cases, an internal combustion engine and an electric machine are selected. In such hybrid drive systems, an energy storage of the electric machine is charged, in that the electric machine is operated as a generator and is driven by the internal combustion engine. When the vehicle is operated in a hybrid operating mode, and the separating clutch is thus engaged, i.e., the drive devices are coupled, both the internal combustion engine and also the electric machine are coupled to a drivetrain of the motor vehicle. In this operating mode, it currently may not yet be recognized whether the internal combustion engine actually delivers a positive torque. If the torque of the internal combustion engine drops out—for example, due to a defect in the system, for example, in the event of failure of the ignition—it is compensated for by a regulating device of the drive system with the aid of the electric machine. The energy storage is discharged, since generator operation of the electric machine may no longer be performed. If a driver of the motor vehicle does not notice that the internal combustion engine is no longer in operation, the motor vehicle may unexpectedly fail for him. Methods for diagnosing the operating status of an individual drive device in a drive system have heretofore rarely been performed, since a measurement of the torque generated by the internal combustion engine or the drive torque jointly generated by the internal combustion engine and the electric machine requires additional measuring devices and is therefore costly.